b'friction has a direct relationship between the soil Where,properties and anchor design.For example, k T = Final Installation Torque - (ft-lb)forclaysoilwouldusuallybegreaterthanfor(Averaged Over the Final 3 to 5 Feet) P uor T u = Ult. Capacity of Torque Anchor - (lb)dry sand.The k for a square bar is generally k = Empirical Torque Factor - (ft -1 )higher than for a tubular pile.Keep in mind that An appropriate factor of safety of 2.0, minimum,thesuggestedvaluesinTable12areonly must always be applied when using design orguidelines.Graph6illustrateshowthe Soil working loads with Equation 3.Table 12.Soil Efficiency Factor k To determine Soil Efficiency Factor, k fromTorque AnchorTypically Suggested field load testing, Equation 2 can be rewritten as:Type Encountered AverageRange k Value, k Equation 2a:Soil Efficiency Factor1-1/2 Square Bar 9 - 11 10 k = (P uor T u ) / T1-3/4 Square Bar 9 - 11 10 Where,2 Square Bar 8.5 ( Compression) 8.5 k = Empirical Torque Factor - (ft -1 )10 - 11 (Tension) 10 P uor T u = Ult. Capacity of Torque Anchor- (lb)2-7/8 Diameter 8 - 9 9 T = Final Installation Torque - (ft-lb)3-1/2 Diameter 7 - 8 8 Always verify capacity on any critical project4-1/2 Diameter 6 - 7 7 by performing a field load test.EfficiencyFactor,kaffectstheultimate Torque Anchor SpacingX: Equation 3 iscapacity of a pile or anchor.It can be seen that used to determine the center-to-center spacing oftheultimatecapacityvariessignificantlywhen Torque Anchors.the same torque is applied to each different shaft Equation 3: Torque Anchor Spacingconfiguration. X = P u /(w) x (FS), orP u= (X) x (w) x (FS)ItisalsoimportanttorefertoTable2forthe Where, X = Product Spacing - (ft)UseableTorqueStrengthvaluestoavoidshaft P u= Ultimate Capacity - (lb)fractures during installation. w= Distributed Load on Foundation (lb/ft)Equation 2:Helical Installation Torque FS = Factor of Safety (Typically 2.0FoundationsT = (P uor T u ) / k, or(P uor T u ) = k x T or Permanent Walls and 1.5 for Temporary Walls)GRAPH 6 -MOTOR OUTPUT TORQUE vs ULTIMATE CAPACITYTorque Efficiency Factor - "k" to Shaft Configuration240220Sq. Shaft (k = 10)2002" Sq. Bar (k = 8.5)Ultimate Capacity x 1,000 lb.180 2-7/8" Dia (k - 9)160 3-1/2" Dia (k - 8)140 4-1/2" Dia (k = 7)120100806040 Earth Contact Products2001 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23Motor Torque x 1000 ft-lbECP Helical Torque Anchors Technical Service Manual2021 Earth Contact Products, L.L.C.2021-09 Chapter 1 - Page 28 All rights reserve'